Electric heating element.



. c. R, WASSELL. A

ELECTRIC HEATING ELEMENT.

APPLICATION man MAY a. 1916.

1,253,915. Patented Jan.15,1918.

[hue/2Z7" QWo/d UNITED STATES PATEN OFFICE.

, CLIFFORD R. WASSELL, OF CHICAGO, ILLINOIS, ASSIG-NOR T CONLON ELECTRICWASHER COMPANY, INC, OF CHICAGO, ILLINOIS, A CORPORATION OF NEW YORK.

Specification of Letters latent. v

ELECTRIC HEATING ELEMENT.

Patented Jan. 15, 1918..

To all whom it may concern:

Be it known that I, CLIFFORD R. WASSELL,

Chicago, in the county of C'ooliand State of Illinois, have invented acertain new and useful Improvement-in Electric Heating Elements, ofwhich the following is a full, clear, concise, and exact description,reference being had to the accompanying drawings, forming a part of thisspecification.

My invention relates to electric heating devices and is concerned withthe provision of an improved heating element to' the end of simplicity,low cost of manufacture, and efiiciency.

According to my invention 1 provide a structure in which the resistancewire, of such material as nichrome or chromel, is suspended aerially ina grid, thereby avoiding the necessity of covering the wire andentailing the-advantage of distributing the heating influence directlyover the desired area.

The arrangement which I provide also lends itself effectively toward acircuit arrangement whereby either one or both of two heatin elementsmay be connected in circuit. mportant among the advantages of myinvention is the particular means whereby the resistance wire issupported, to the end of simplicity in assembling the entire structure.

In the accompanying drawings,

Figure l is an elevational view of the structure of my invention; I

Fig. 2 is a sectional view taken on the plane of the line 2, 2, of Fig.1, and looking in the direction indicated by the arrows;

Fig. 3 is a sectional view taken on the plane of the line 3, 3, of Fig,1, andlooking in the direction indicated by the a'rows;

Fig. 4 is a sectional viewtaken on the plane of the line 4:, a, of Fig.1, and looking in the direction indicated by the arrows;

Fig. 5 is a perspective view of one of the supporting members; and

Fig. 6 is a perspective view of one of the spacing members.

The grid is in the form of a rectangular frame 7 having the spider arms8, 8. Each of these spider arms is made desirably of sheet metal and isin channel formation, as illus trated in Figs. 3 and 4. Within each ofthese spider arms there are disposed two strips 9, 9, of insulatingmaterial, these strlps being laid face to face, as shown, and afterinsertion in the channel, held in place by'clamping over the extensions11 11, of the sheet material, as illustrated. One of these insulatingstrips 9 is slotted at proper intervals upwardly from the bottom, whilethe other strip is slotted downwardly from the top at the sameintervals, these slots being illustratedat 10.- depth that when the twostrips are laid together they. overlap leaving a continuous opening 12through which the resistance wire 13 may pass. Thi is the structure ofeach of the spider arms.

It will now be seen that in assembling the structure the spider arms areall made ready for the reception of the insulating strips and theinsulating strips which are slotted downwardly from the top aredisposed'in place. Theresistance wire or wires are then laid in theseslots and after the resistance wire or wires have been all properlyarranged, the other set of insulating strips 9, those slotted upwardlyfrom the bottom, are put 111 place,

being slipped over the resistance wires, as illustrated. After the twostrips have thus been brought in complete face to face register, theyfully occupy the channel in which they are disposed and theextensionsll, 11', hereinbe'fore referred to, are clamped over tocomplete the structure.

The resistance wires 13, 13 remain uncovered and therefore fullefficiency is secured,

the grid being properly mounted in an oven or other adaptable place.

With this arrangement, it will be seen that the resistance wires may bedistributed over a considerable area in perfect safety and-with ampleprotection. A I preferably arrange the resistance wire or wires 1nconvolutlon and These slots are of such in the present form I have showna double I means of screws 19, 19, and made to intersect whereverconvenient.

In order that the expansion of the reslstance wire or wires, due to theheat, may not cause them to sag to the extent of short-cireuitingconvolutions, or certain parts thereof, I provide spacers 20, 20,illustrated particularly in- Fig. 6. These spacers are provided withslots 21, 21, cut alternately from opposite sides to adepth a littlebeyond the center line, andthese spacers are interposed between thespider arms, as illustrated, with the resistance wire or wires laid inthe slots, as shown, in order to keep them properly spaced apart. Themembers 20 and 9 are, of course, made of such material, as will properlyresist the heat which is generated.

I claim: 1. In an electric heating device, two strips of insulatingmaterial, each of said strips having a lateral slot therein, said stripsheing laid face to face with said slots opp0' sitely in alinement and sothat the inner ends of said slots register, and a heating Wire passingthrough the registering portions of said slots.

' 2. In an electric heating device, two strips of insulating material,each of said strips having a lateral slot therein, said strips beinglaid face to face with said slots oppositely in alinement and so thatthe inner ends .of said slots register, a heating wire passing ofinsulating material, each of said strips having a lateral slot therein,said strips being laid face to face with said slots oppositely inalinement and so that the inner ends of said slots register, a heatingWire passing -through the registering portions of said slots, and ametallic carrier for saidstrips, said carrier being of sheet materialand being clamped over said strips to hold them together. I I

4:. In combination, agrid, two uncovered heating units spirally arrangedtherein, a

pair of insulating strips laid face to face and provided with oppositelydisposed alin ing slots forming openings, sheet metal holders formingstrips provided with flanges for clamping engagement with the strips tosupport the same, and spaced strips for location between adjacentsupports for. the heatin unit provided with oppositely disposed slots toreceive the heating unit and space adjacent convolutionsof the same.

In witness whereof, I hereunto subscribe my name this 29th day of April,A. D. 1916.

GLIFFURD R. WASSELL.

